Carbon dioxide has a large number of uses. For example, carbon dioxide is used to carbonate beverages, to chill, freeze and package seafood, meat, poultry, baked goods, fruits and vegetables, and to extend the shelf-life of dairy products. It is an important environmental component in industrial waste and process water treatment as a replacement for sulfuric acid to control pH levels. Other uses included drinking water treatment, an environmentally-friendly pesticide and an atmosphere additive in greenhouses to improve the growth of vegetables.
Generally carbon dioxide is produced by purifying a waste stream which is a by-product of an organic or inorganic chemical process. The waste stream comprising the carbon dioxide is condensed and then processed in a distillation column to produce the product grade carbon dioxide.
As the demand for carbon dioxide continues to increase, more marginal sources of carbon dioxide are being used to supply the crude carbon dioxide feed to the purification system. Such marginal feeds may include significant amounts of light contaminants and thus require significantly more energy to carry out the requisite liquefaction prior to the rectification into product.
Accordingly it is an object of this invention to provide a system which can effectively process a crude carbon dioxide feed stream which contains light contaminants in a more energy efficient manner than that possible with conventional carbon dioxide processing systems.